Components having micromechanical sensor elements are frequently used for detecting different physical variables (pressure, temperature, air mass, acceleration, yaw rate), in particular in the automotive industry. Typically, measuring elements on membranes, which are situated above a cavity, are frequently used. For creating the membrane or the cavity, bulk micromechanics, in which the structures are machined out of solid material, are known in addition to surface micromechanics in which layer stacks made up of sacrificial layers and function layers are deposited, structured, and selectively removed.
International Published Patent Application No. 02/02458 and German Published Patent Application No. 100 32 579, for example, describe a method in which different porous areas are formed in a substrate for creating a hollow space beneath the membrane.
It is known from German Published Patent Application No. 100 30 352 to support a membrane above a cavity via stabilization elements. Such stabilization elements are able to be created using etching processes, for example, which selectively remove or porously etch differently doped areas from a substrate as is also described in non-prepublished German Patent Application No. 102004036035 and German Patent Application No. 10358859.
Another possibility for creating a hollow space in a substrate is described in German Published Patent Application No. 101 14 036. In the method described in this publication, an aperture is initially created in the substrate which then undergoes a temperature treatment. Due to the temperature selection and the time period of this temperature, a hollow space is formed in the depth of the substrate under simultaneous closing of the aperture. By using a plurality of adjoining apertures, this method makes it possible to create a membrane with a hollow space situated underneath.
European Published Patent Application No. 1 043 770 describes a method for creating a cavity in which at least one trench is initially created in a substrate via a first etching step. Subsequent to a passivation of the trench walls, the cavity is formed during a second anisotropic etching step. Finally, for forming a membrane above the cavity, a monocrystalline layer is grown on the substrate.